The present invention relates to metal casting apparatus and methods of casting and more particularly to the use of a semi-permanent mold cope for casting aluminum. More particularly, the present invention is directed to an improved apparatus and method of casting aluminum with the use of precision sand and controlled cooling through the use of a semi-permanent mold cope.
For purposes of explanation, reference will be made to the use of the present invention with respect to the casting of engine blocks. It should be understood by those of ordinary skill in the art that the invention is not limited to use in casting engine blocks and can be used in casting other products.
Engine blocks have traditionally been cast from iron using sand casting. One of the distinct advantages of castings is that hollow or reentrant sections can be included with relative ease. Generally, sand casting involves the creation of a pattern that is placed in a mold or flask. The mold is then filled with sand. The sand includes a binder that is activated to bind the sand together. After the binder has been activated, the pattern is removed and molten metal can be poured into a sprue that is connected to runners that are fluidly connected to the sand casting. Risers are also used to provide metal to the casting as the metal cools and shrinks. The risers are connected to the runners. After the mold has been filled and allowed to cool, the sand is extracted from the product.
Although iron has traditionally been used to cast engine blocks, aluminum is becoming more desirable because of its reduced weight. Casting aluminum engine blocks from sand castings is relatively new and has inherent problems. One of the biggest problems is the difficulty in providing more rapid cooling at desired areas of the aluminum engine block. Traditionally, a chill provided quicker cooling. A chill is a portion of the mold that is colder than other mold portions and causes the adjacent molten metal to solidify faster than remote metal causing the more rapidly cooled area to have increased mechanical properties. It is important to provide targeted increased mechanical properties in the product being cast. For example, when casting an engine block, the bottom of the engine block where the crankshaft is connected needs to have greater mechanical properties than other portions of the engine block.
Another problem with sand casting in general is the space that is required to house the casting operation and the time involved in the casting process. What is needed is a more compact quicker casting operation.
The present invention is an improved casting system including a precision fill system, a turntable loading system, and a precision mold system with semi-permanent mold cope application. The improved fill system includes a laser measurement device and a computer system for monitoring and controlling the fill rate of a casting mold with molten metal. Precisely controlling the fill rate of the mold results in a stronger casting. The turntable loading system of the present invention includes a turntable whereupon numerous molds may be loaded, rotated into position with a furnace, and rotated again to cool. The turntable system speeds up the casting process and uses a minimum footprint of space in the casting facility. The semi-permanent mold cope system of the present invention permits the use of a removable semi-permanent mold cope or to more rapidly cool certain areas of the mold. In this way, the casting can be easily provided with desired qualities at precise locations and post solidification operations can be more precisely and economically performed.